The furnace of this invention is an improvement in Gell et al U.S. Pat. No. 3,440,321 issued Apr. 22, 1969 and assigned to the same assignee as the present application. The improvement comprises adapting the circuitry of this patent to sidewall electrodes.
Vertically and horizontally spaced rod electrodes in the sidewalls of electric furnaces, even in square electric furnaces, are shown in the Doolittle U.S. Pat. No. 656,600 issued Aug. 21, 1900, and in Horry U.S. Pat. No. 757,618 issued Apr. 19, 1904 and U.S. Pat. No. 771,250 issued Oct. 4, 1904, and Penberthy U.S. Pat. No. 2,749,378 issued June 5, 1956. However, all these patents disclose furnaces which operate on three or more phase currents.